The present invention relates to a method of separating from flue gases such gases as are aggressive and injurious to the environment, e.g. hydrogen chloride, sulphur dioxide or sulphur trioxide or the like gases, by making the flue gases react in an atomizing conditioning plant with a chemical such as sodium hydroxide or sodium carbonate, calcium hydroxide or calcium carbonate or another chemical which is reactive with the said gas or gases, the products of the reaction and the non-reacted surplus of chemical being removed from the plant as a dry pulverous product, part of which is recirculated through the plant with a view to obtaining a higher degree of utilization.
From application No. 4830/77 for a Danish patent a method is known of removing hydrogen chloride from flue gas originating from the burning of waste materials by absorbing the hydrogen chloride with an alkaline agent, in which said method the flue gas is introduced with a temperature between 200.degree. and 330.degree. C. into a chamber, wherein an aqueous solution of alkaline metal carbonate or an aqueous suspension of calcium hydroxide, calcium carbonate or magnesium oxide is atomized by means of an atomizing wheel, the quantity of solution or suspension being so adjusted that the temperature with which the flue gas leaves the chamber is higher than 125.degree. C., and the material formed by the drying of the atomized solution or suspension leaves the chamber as a dry, freely flowing powder.
In order to improve the efficiency of this process, in which the chemicals must be supplied in stoichiometric surplus, it has been suggested that some of the powder produced be returned to the atomizer as a solution or suspension together with fresh chemical. However, the viscosity of the solution or suspension that is to be atomized sets narrow limits to the quantity of pulverous material that can be recirculated in this way through the plant and consequently also to the useful effect.
It should be noted at this point that in consideration of the functionality of subsequently connected textile and/or electric filters there is a limit to the amount of water that can be supplied to the flue gases in the conditioning process.